Polymeric compositions and their production and uses

ABSTRACT

A clear personal care or other aqueous gel is formed from dry polymer particles which are free of materials which render the gel cloudy and which are made by reverse phase emulsion polymerisation. The polymerisation process involves distilling water from the emulsion in the presence of sufficient non-aqueous liquid to prevent breakage of the emulsion and then washing the polymer particles with isopropanol or other suitable solvent and evaporating the solvent.

This invention relates to powdered polymer having very small primaryparticle size and which is soluble or swellable in water to form ahomogeneous, clear, gel, and to the production of this polymer.

It is conventional practice to thicken an aqueous composition by addingwater-soluble or water-swellable thickening polymer to the composition.It is often desirable to provide this polymer in powder form, namely asa dry product in the form of particles, which may be individual primaryparticles or which may be aggregates of such particles and whichdisintegrate when mixed into water.

Powdered water-soluble or water-swellable polymer particles can be madeby various polymerisation processes including bulk polymerisationfollowed by comminution, solution polymerisation followed by drying (forinstance by spray drying), precipitation polymerisation followed byrecovery of the precipitate and drying, reverse phase beadpolymerisation followed by recovery of dry beads and comminution ifsmall primary particles are required, and emulsion polymerisationfollowed by recovery of the polymer from the emulsion. Examples of bulkand bead polymerisations to give coarse (preferably all above 150 μm)superabsorbent powders are in EP-A-872491, but these cannot give a clearhomogeneous gel because the coarse beads retain individual integrity.

Each method gives a powdered product having different physical form(such as shape and size) and also having different types and degrees ofcontamination. Precipitation polymerisation and reverse phase emulsionpolymerisation is generally preferred when a very small primary particlesize (all below 20 μm) is required.

The selection of the polymerisation method and the monomers to bepolymerised also influences the molecular weight (including themolecular weight distribution) which is conveniently achieved by thepolymerisation. For instance some anionic polymers can conveniently bemade by methods such as precipitation polymerisation to give polymershaving good molecular weight properties and low contamination, but suchtechniques tend to be less satisfactory for cationic monomers. In orderto obtain the optimum molecular weight properties using cationicmonomers it is generally preferred to use reverse phase emulsionpolymerisation, but this tends to result in emulsions, or powderedproducts, which are contaminated with materials that reduce the clarityof the final gel.

Clarity of the gel is particularly desirable in personal carecompositions such as cosmetic compositions and topical pharmaceuticalcompositions. The thickening polymer in these frequently is a cationicpolymer, for instance as described in U.S. Pat. No. 4,806,345 and U.S.Pat. No. 5,603,926. The problem of clarity is mentioned in EP-A-824914.This disclosure describes cationic thickeners which are in the form ofstable emulsions, but we are concerned with the problem of providing athickener in the form of a finely divided powder.

It would therefore be desirable to produce an improved way of making avery finely divided powdered polymer which can give a gel having goodclarity, and in particular it would be desirable to provide this wherethe polymer is a cationic polymer.

According to one aspect of the invention, we make a dry powder formed ofprimary particles, or aggregates of primary particles, of awater-soluble or water-swellable polymer wherein the powder dissolves orswells in water to form a gel, by a method which comprises

forming an emulsion of aqueous monomer in non-aqueous liquid, optionallyin the presence of an emulsifier,

initiating polymerisation and allowing polymerisation to complete,

distilling water from the emulsion until the emulsion is substantiallydry, the distillation being conducted while maintaining a sufficientamount of the non-aqueous liquid to prevent breakage of the emulsion,

separating the non aqueous liquid from the polymer particles by aprocess comprising washing the substantially dry emulsion, or a slurryor cake of dry polymer particles separated from it, with an organic,volatile, solvent which is a solvent for non-aqueous liquid and for theemulsifier (if used) and which does not dissolve or swell the polymerparticles and which is substantially miscible with water,

separating the washed polymer particles as a cake or slurry of theparticles wetted by the solvent, and

evaporating the solvent from the cake or slurry and thereby providingthe dry powder.

The polymer is made by reverse phase emulsion polymerisation of watersoluble or water swellable ethylenically unsaturated monomer or monomerblend. Any of the conventional cationic, non-ionic and anionicethylenically unsaturated monomers can be used, together with blends ofthe monomers.

The polymer is preferably cationic. The method is particularlyadvantageous for making cationic powdered thickeners, and especially forproviding such thickeners which give a clear gel. Accordingly themonomer or monomer blend which is polymerised preferably contains one ormore cationic ethylenically unsaturated monomers, or a blend of suchmonomer with non-ionic monomer and/or anionic monomer. The amount ofcationic monomer is preferably such that the monomer is predominantlycationic.

According to another aspect of the invention, we provide a powder formedof primary particles, or aggregates of primary particles, of awater-soluble or water-swellable polymer wherein the product dissolvesor swells in water at a gelling pH to form a gel, and wherein theprimary particles preferably have a size below 20 cm and have thecharacteristic, substantially spherical, structure of polymer particlesmade by reverse phase emulsion polymerisation, and the composition givesa 0.5% gel in water, wherein the gel has a clarity of at least 90% at430 nm (as explained below). The clarity is preferably at least 93% or95%, and most preferably it is at least 97 or 98%.

Whether or not the polymer particles have the characteristic,substantially spherical, structure including shape of particles made byreverse phase emulsion polymerisation can easily be determined bymicroscopic examination. Particles made by spray drying may besubstantially spherical but they can be seen by microscopic examinationto be very porous and shell like and so the product includes pieces offractured shell. Particles made by solution, bulk or precipitationpolymerisation all have characteristic, non-spherical, shapes. Particlesmade by reverse phase emulsion polymerisation have a dry size typicallyin the range 0.5 to 20 μm, often 1 to 10 μm, and when examined by amicroscope are predominantly solid spheres. For instance at least 80%(by weight) of the particles in any particular microscopic imagetypically are truly spherical or substantially spherical, although therecan be minor amounts of broken, pear-shaped or other deformed solidparticles. Accordingly, the primary particles of the invention havethese typical characteristics. The mean particle size is generally inthe range 0.5-10 μm. The mean size is usually at lest 1 μm. It isusually below 5 μm and so may be, for instance, 1-2 μm. Generallysubstantially all the particles (e.g., at least 95% by weight) are below20 μm and preferably below 10 μm

Normal ways of conducting reverse phase emulsion polymerisation of amonomer result in the particles being contaminated by significantamounts of cloud-forming impurities which were included as essentialcomponents in the reverse phase emulsion polymerisation process. Forinstance it is normal to use a significant amount of emulsifier in orderto stabilize the emulsion initially and it is normal to select anon-aqueous liquid as the continuous phase, and optionally also apolymeric stabilizer, to improve the stability of the emulsion,especially during subsequent evaporation of water from it, and parts ofthese remain on the particles.

The powdered products of the invention are preferably free ofcloud-forming amounts of polymeric stabilizer, hydrocarbon andemulsifier.

As a result of using reverse phase emulsion polymerisation for makingthe polymer particles, it is easily possible to optimize the eventualviscosifying properties because reverse phase emulsion polymerisationallows this to be done, in accordance with common general knowledge,much more easily than is achievable when using other types ofpolymerisation, especially when the polymer is cationic.

Preferred cationic monomers are cationic esters of acrylic ofmethacrylic acid, preferably a cationic methacrylate. Accordingly, thepolymer is generally a polymer of 50 to 100 mole percent water solublecationic ester of methacrylic acid and 0 to 50 mole percent of otherwater soluble ethylenically unsaturated monomers. If comonomer ispresent, it may be non-ionic (for instance acrylamide) or in someinstances a minor amount of anionic comonomer can be present.

The preferred cationic monomer is an acid addition or quaternaryammonium salt of a dialkylaminoethyl methacrylate, and is mostpreferably the methyl chloride quaternary salt of dimethylaminoethylmethacrylate.

The polymer can be linear but is usually lightly cross linked and so itis normally formed in the presence of a cross linking agent. As isconventional, this cross linking agent can be a polyethylenicallyunsaturated material. The amount of cross linking agent is usually lowin order that the powder particles swell and dissolve in water to form aclear, homogeneous gel instead of remaining as discrete, or partlydiscrete, swollen particles. Generally the cross linking agent is apolyethylenically unsaturated material in an amount of below 200 ppm,often below 130 ppm, e.g., 50-100 ppm, by weight of monomer.

The preferred polymers are homopolymers of the cationic ester ofmethacrylic acid, copolymerized with, usually, 0.001 to 0.1 mole percent(preferably below 130 ppm by weight) of a polyethylenically unsaturatedcross linking agent.

Suitable cross linking agents are methylene bis acrylamide or any of theconventional covalent cross linking agents used for making swellableviscosifying polymers.

The non-aqueous liquid is preferably volatile and preferably is ahydrocarbon. Preferred hydrocarbons are aliphatic hydrocarbons,preferably branched or linear isoparaffins. They preferably have aboiling point at normal pressure of below 200° C., most preferably inthe range 150 to 180° C. The boiling point under normal pressure ispreferably above 90° C. and most preferably is above 100 or 120° C. Thisallows for the polymerisation exotherm to run at optimum temperaturesfor polymer quality without volatilization of the non-aqueous liquid.Examples of suitable non-aqueous liquids are the materials sold underthe trade names Isopar G and Multipar G.

Preferably the continuous phase of the emulsion consists substantiallyonly of the hydrocarbon or other non-aqueous liquid. The continuousphase preferably is wholly or substantially free of non-volatilenon-aqueous liquid and/or polymeric stabilizer (both of which areconventional in prior processes).

It is usually desirable to include some emulsifier in order tofacilitate formation and stability of the emulsion but in the inventionthe amount of stabilizer preferably is minimized by conducting thepolymerisation on a more dilute solution of monomer than is conventionalin reverse phase polymerisation for making the relevant polymers. Thusconventional processes usually have a monomer concentration of aboveabout 72% (monomer based on monomer plus water) and with the totalamount of water in the emulsion, based on the total weight of theemulsion, often being around 15%. In the invention, however, we preferto use more water in the emulsion so that the aqueous monomer solutionis more dilute.

Typically the concentration of monomer is below 70% and is usually inthe range 50 to 68% (based on monomer plus water). The amount of water,based on the total weight of the emulsion, is now usually in the range20 to 40%, preferably 22 to 30%. Typically the amount of polymer is 35to 55%, often around 40 or 45% to 50%, and the amount of the volatilenon-aqueous liquid is generally 20 to 40%, often around 25 to 35%.

With such amounts, and with routine selection of the volatilehydrocarbon or other non-aqueous liquid, it is possible to minimize, andsometimes even to eliminate, the emulsifier while maintaining emulsionstability. If emulsifier is being used then it can be any of theconventional emulsifiers for water-in-oil polymerisation, typicallyemulsifiers having HLB of 3.5 to 6. A preferred material is the materialcommercially available under the trade mark Span 80. Other suitableemulsifiers include glyceryl mono-oleate and sorbitan sesqui-oleate.

The amount of emulsifier is usually from 0.1 or 0.5 to 1, 1.5 or 2%based on the weight of emulsion or 0.2 to 2, 3 or sometimes 4% based onthe weight of monomer.

The emulsion may be formed in conventional manner by homogenization ofthe oil and aqueous phases to provide an emulsion having a particle size(for the aqueous particles) which will provide the desired primarypolymer particle size after polymerisation and drying.

Polymerisation may be achieved by purging the emulsion with nitrogen gasand adding initiator. This addition is usually made throughout most orall of the period of the polymerisation reaction. In order to facilitaterapid distribution of the initiator throughout the emulsion, some or allof the initiator is preferably added as an emulsion or solution innon-aqueous liquid. Thermal initiator can be used as part or all of theinitiator system but it is often adequate to rely on a redox system, forinstance with sodium metabisulphite being added as an emulsion innon-aqueous liquid and t-butyl hydroperoxide or other redox couple beingadded as a solution in non-aqueous liquid. The rate of addition and theduration of addition is conducted in conventional manner and theprogress of the polymerisation is monitored in conventional manner.

When it is judged that the polymerisation has gone to completion, theemulsion is dried by distillation of the aqueous phase from it.Distillation is normally conducted under reduced pressure with reflux ofthe non-aqueous liquid while the water is removed.

It is necessary to ensure that the emulsion does not break during thisprocess, i.e., it must not break to an extent sufficient to causeserious congealing of the polymer particles. It is often desirable toadd an additional amount of the non-aqueous liquid prior to or duringthis distillation stage so as to reduce the risk of breakage of theemulsion by maintaining the liquid content of the emulsion substantiallyconstant. For instance the amount of additional non-aqueous liquid whichis added may be 0.2 to 1.5 times, often around 0.5 to 1 times, theamount of water which is being removed.

The distillation is conducted until the water removal has dropped to avery low rate, preferably near zero. This occurs when the emulsion issubstantially dry, for instance having a water content (based on theweight of polymer) of below 10% and usually below 5% by weight.

The dry polymer particles (and aggregates of these) are then separatedfrom the non-aqueous liquid by a process comprising washing thesubstantially dry polymer particles with an appropriate volatilesolvent. The solvent may be added to the entire mixture of non-aqueousliquid and polymer particles (so that the entire emulsion is washed) orsome of the non-aqueous liquid may be separated, for instance byfiltration or centrifugation, before the washing to form a slurry orcake, and it may be this slurry or cake which is washed.

The amount of the solvent is often such that the percentage of polymer,based on polymer and solvent, is 1 to 50%, often 1 to 15%, preferably 2to 10%.

After the washing, the polymer particles are separated from the solvent,again usually by a filtration or centrifugation or other physicalseparation step, to form a cake or slurry. The particles can be washedagain with more solvent if required. Preferably the content of polymerin the final cake or slurry of particles and solvent is at least 30%,preferably at least 45%, and most preferably at least 50, 55 or 60%, upto 70% or more.

Residual solvent is then evaporated from the resultant cake or slurry ofpolymer particles, for instance by oven or other warm air drying so asto provide the desired dry powder. This may be formed mainly ofindividual primary particles but it is generally desirable that many orsubstantially all of the primary particles are present as aggregatessince this reduces handling problems and increases the bulk density. Theaggregates should be readily disintegratable upon stirring into themedium which is to be thickened so as to release the primary particlesinto the medium.

In general, clarity improves as the amount of solvent used for thewashing is increased and as the amount of solvent which has to beevaporated is reduced.

The solvent which is used for the washing must be a solvent for thenon-aqueous liquid of the continuous phase of the emulsion in order thatthe solvent washes that liquid away from the particles. If emulsifierwas used, it must also be a solvent for the emulsifier, so as to washthat away from the particles. Whether or not any particular solvent is agood solvent for any particular emulsifier can be checked by a simpleroutine test. The solvent must not dissolve, soften or swell the polymerparticles to such an extent as to detract from the powder properties ofthe final product and preferably the solvent does not cause anydissolution or swelling of the particles.

The solvent must be sufficiently volatile that it can be convenientlyevaporated by warm air or other suitable drying technique. Preferablythe solvent is sufficiently volatile that there is no risk of any tracesof solvent remaining on the particles after drying. However, it is, inany event, desirable that the solvent is substantially fully misciblewith water so that any traces of solvent on the particles will not causecloudiness of the final gel.

The solvent is usually a polar solvent. Preferably it is a C1-4 alcoholor ketone. Although methanol has been proposed previously for washinglarge superabsorbent anionic polymer particles in EP 872941, methanoland ethanol may tend to cause too much softening or swelling of the verysmall particles of polymers in the invention (especially the cationicpolymers) with the result that the primary particles may tend to fuseinto coarse granules which do not disintegrate easily into the primaryparticles. Acetone has also been proposed but tends to be an inadequatesolvent for some grades of Span 80 or other emulsifier. Accordinglypreliminary testing will often show that methanol, ethanol and acetoneare not entirely satisfactory with some or most powdered polymers in theinvention. The preferred solvent is generally isopropyl alcohol.

In some instance it is desirable to include with the solvent a smallamount of a water-miscible cosolvent for any emulsifier. Suitablecosolvents are emulsifiers having a long ethoxy chain whereby thehydrophilic component promotes dissolution of the emulsifier into thevolatile solvent. An example is ethoxylated sorbitan monolaurate,typically having more than ten ethoxy groups, preferably twenty ethoxygroups. The addition of a cosolvent in this manner can help to providefinal “polishing” of the clarity of the gel. Alternatively the cosolventemulsifier may be incorporated into the gel formed from the dry product.

The dry product, consisting of the primary particles or aggregates ofprimary particles, can then be incorporated into a personal care orother composition as a viscosifier in conventional manner. Thecomposition should be formulated to have a pH at which the polymer gelsto form a gel of the dissolved or swollen polymer particles, i.e., thegelling pH. For cationic polymers, the gelling pH can be as low as 2.5.Although the composition often has pH below 7, for instance 4.5 to 6.8,stable gels of cationic polymers can be formed in the invention havingpH values higher than this, for instance up to 9 or even 10 or 10.5,when using cationic polymers in accordance with the invention. Naturallythe optimum pH depends on the monomers which are used and on the othercomponents of the composition.

As a result of providing a powdered composition formed of particles ofwater-soluble or water-swellable polymer free of cloud-forming amountsof polymeric stabilizer, hydrocarbon or other non-aqueous liquid, andemulsifier, despite having been made by reverse phase polymerisation,the powdered composition gives a clear gel in water. In particular, theprocess of the invention can easily be conducted so that the compositiongives a gel which has a clarity of at least 85% and preferably at least90%, and most preferably at least 93% or, especially, at least 95%.

In this specification, all clarity values are determined at 430 nm,since this gives maximum resolution. The protocol is designed fordetermining the clarity of a gel formed by dissolving cationic polymerin deionizer water, without any deliberate pH adjustment. If therelevant polymer does not dissolve or swell to an optimum extent whendissolved merely in water, then some pH adjustment may be applied. Asuitable protocol is described in the Noveon Standard Test Procedure485-D September 1993. A more detailed protocol is as follows:—

1. The clarity measurement is performed on a 0.5% solution of polymer indeionizer water, using a Colorimeter such as a Brinkmann ProbeColorimeter Model PC 801.

2. The polymer is dried at 80° C. for 1 hour.

3. The polymer is allowed to cool and 1.0000 g+/−0.002 weighedaccurately on an analytical balance into a weigh boat.

4. 199 g+/−0.02 g deionizer water is weighed into a 250 ml plasticbeaker.

5. The beaker is clamped in place and stirred using a 50 mm radial flowimpeller, placed near the bottom of the beaker.

6. The polymer is added slowly to the deionizer water to avoid clumpingsince the presence of agglomerated particles is would interfere.

7. After the solution starts to thicken the stirrer speed is increasedto 2000 rpm for 5 minutes to ensure full hydration.

8. Using a spatula, a portion of the solution is transferred to a 50 mLcentrifuge tube.

9. The tube is placed in the centrifuge and spun for five minutes at themaximum speed setting. Centrifugation is for elimination of air bubblessince these would interfere.

10. The calorimeter is turned to % T and a 430 nm filter is provided,and a five minute warm-up period is allowed.

11. A 1 cm cuvette is filled with deionizer water and the 100% T CoarseControl Knob is adjusted until the reading indicates 100.0% or veryclose. The Fine Control is used to obtain an exact reading of 100.0%.

12. Using a spatula, a portion of the solution is transferred to a 2 cmcuvette avoiding air entrapment.

13. The % Transmission (or Clarity) is read directly from theinstrument.

The following is an example of the invention.

An emulsion was formed of 6673 g of a 75% aqueous solution of the MeClquaternary salt of dimethylaminoethyl methacrylate, 12.8 g citric acid,1043 g deionizer water, 11.4 g Tetralon B and 0.693 g methylene bisacrylamide in 3227 g Multipar G containing 80.6 g Span 80 as emulsifier.The emulsion was made by forming the aqueous phase and the oil phaseseparately and then homogenizing the oil phase into the aqueous phasefor 20 minutes using a Silver son with cooling to keep the temperatureat or below 20° C. The emulsion was then transferred to a conventionalpolymerisation pot, degassed for 30 minutes and held under nitrogen. A0.5% emulsion of SMBS in Isopar G and a 0.5% solution of TBHP in IsoparG were fed into the emulsion at 100 ppm per hour, and the temperaturewas monitored every 60 seconds to ensure that the polymerisation wascontinuing satisfactorily.

After the completion of the full exotherm was observed, the initiatorfeeds were continued for a further 20 minutes. They were thenterminated, and the reaction mixture was left stirring for a further 20minutes to allow polymerisation to complete.

200 g of the product was removed from the vessel and was diluted with 50g Isopar and was then subjected to distillation using a rotaryevaporator under full vacuum at a temperature ranging between 25 and 80°C. until the final product was a dry emulsion of the dry polymerparticles in hydrocarbon.

Isopropyl alcohol in an amount of 95% based on the weight of polymer andisopropyl alcohol was then mixed with the product so as to wash thepolymer particles. The resultant mixture was then separated bydecantation and centrifugation and the resultant cake had a polymercontent of 61%. The residual solvent was evaporated from the cake in anoven at less than 60° C. until a dry weight (1 gm for 1 hour at 110° C.)of at least 90% is achieved (for instance at 40° C. for 2 days).

The resultant powder consisted of substantially spherical solid primaryparticles and easily disintegratable aggregates of these. The powder waseasily distributed into water to give a clear gel having a clarity of98% at 430 nm.

In other tests, a clarity of 99% was obtained when the amount ofisopropyl alcohol was 98.75% and the resultant cake or slurry wasconcentrated to 58% polymer before the drying, but a clarity of only 75%was obtained when the amount of isopropyl alcohol was 95% but theresultant cake or slurry only contained 46.5% polymer prior to the finalevaporation of solvent in the oven. In another example a clarity of 95%was achieved when the amount of isopropyl alcohol was 97.5% and theslurry or cake, before final evaporation in the oven, had a polymercontent of 42.3%.

In another process where the clarity, when using isopropyl alcoholalone, was 88%, a clarity value of above 95% was achieved by includingwith the solvent 1% of 20 mole ethoxylate of sorbitan monolaurate.

1. A process of making a dry powder formed of primary particles, oraggregates of primary particles, or a polymer wherein the primaryparticles have a size below 20 μm and the powder can dissolve or swellin water to form a clear gel, the process comprising forming an emulsionof aqueous ethylenically unsaturated cationic monomer in non-aqueousliquid optionally in the presence of an emulsifier, initiatingpolymerisation and allowing polymerisation to complete, distilling waterfrom the emulsion until the emulsion is substantially dry, thedistillation being conducted while maintaining a sufficient amount ofnon-aqueous liquid in the emulsion to prevent breakage of the emulsion,separating the non-aqueous liquid from the polymer particles by aprocess comprising washing the substantially dry emulsion, or a slurryor cake of dry polymer particles separated from it, with a volatileorganic solvent which is a solvent for the non-aqueous liquid and forthe emulsifier (if used) and which does not dissolve or swell thepolymer particles and which is substantially miscible with water,separating the washed polymer particles as a cake or slurry of thepolymer particles wetted by the solvent, and evaporating the solventfrom the cake or slurry and thereby providing the dry powder, whereinthe powder is swellable in water to form a gel with optical clarity. 2.A process according to claim 1 in which the polymer is a cationicpolymer.
 3. A process according to claim 1 in which volatile non-aqueousliquid is added to the emulsion after the polymerisation and before orduring the distillation of water from the emulsion.
 4. A processaccording to claim 1, in which the amount of the volatile solventutilised for washing the substantially dry emulsion or the polymerparticles separated from the dry emulsion is from 85 to 99% based on theweight of solvent and polymer.
 5. A process according to claim 1, inwhich the amount of the volatile solvent in the slurry or cake which issubjected to the evaporation is at least 50% by weight based on theweight of solvent and polymer.
 6. A process according to claim 1, inwhich the volatile solvent is isopropyl alcohol.
 7. A process accordingto claim 1, in which the concentration of monomer in the emulsion isbelow 70% by weight based on the weight of monomer and water and theemulsion contains 35 to 55% by weight of the monomer, 20 to 45% byweight of the non-aqueous liquid and 20 to 40% by weight of the water,all based on the weight of monomer, volatile non-aqueous liquid andwater.
 8. A powder formed of particles, or aggregates of particles, of acationic polymer wherein the product can dissolve or swell in water toform a gel, characterised in that the particles have a size below 20 μmand have the characteristic, substantially spherical, shape of polymerparticles made by reverse phase emulsion polymerisation, and thecomposition gives a 0.5% gel in water at a gelling pH wherein the gelclarity is at least 90% at 430 nm.
 9. A product according to claim 8 inwhich the cationic polymer is a cationic polymer of 50 to 100 molepercent of a water soluble cationic ester of methacrylic acid, 0 to 50mole percent other water soluble ethylenically unsaturated monomer, andoptionally cross linking agent, and in which the polymer is preferably across linked homopolymer of the methyl chloride quaternary salt ofdimethylaminoethyl methacrylate.
 10. A personal care compositionthickened by a composition made by a process according to claim
 1. 11. Apersonal care composition thickened by a product according to claim 8.12. A process according to claim 1, in which the amount of the volatilesolvent utilised for washing the substantially dry emulsion or thepolymer particles separated from the dry emulsion is from 90 to 98%based on the weight of solvent and polymer.
 13. A process according toclaim 1 in which the cationic polymer is a cationic polymer of 50 to 100mole percent of a water soluble cationic ester of methacrylic acid, 0 to50 mole percent other water soluble ethylenically unsaturated monomer,and optionally cross linking agent, and in which the polymer ispreferably a cross linked homopolymer of the methyl chloride quaternarysalt of dimethylaminoethyl methacrylate.